Every mcount() call in the MIPS 32-bit kernel is done as follows:
[...]
move at, ra
jal _mcount
addiu sp, sp, -8
[...]
but upon returning from the mcount() function, the stack pointer
is not adjusted properly. This is explained in details in 58b69401c797
(MIPS: Function tracer: Fix broken function tracing).
Commit ad8c396936e3 ("MIPS: Unbreak function tracer for 64-bit kernel.)
fixed the stack manipulation for 64-bit but it didn't fix it completely
for MIPS32.
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
---
Hopefully this is the final version ;)
Changes since v3:
- Rework v3 to unbreak dynamic tracing on MIPS32
Changes since v2:
- Also fix the case where the function graph tracer is enabled
Changes since v1:
- Also fix the case where the tracer is actually enabled
---
arch/mips/kernel/mcount.S | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index 5d25462de8a6..2f7c734771f4 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -129,7 +129,11 @@ NESTED(_mcount, PT_SIZE, ra)
nop
#endif
b ftrace_stub
+#ifdef CONFIG_32BIT
+ addiu sp, sp, 8
+#else
nop
+#endif
static_trace:
MCOUNT_SAVE_REGS
@@ -139,6 +143,9 @@ static_trace:
move a1, AT /* arg2: parent's return address */
MCOUNT_RESTORE_REGS
+#ifdef CONFIG_32BIT
+ addiu sp, sp, 8
+#endif
.globl ftrace_stub
ftrace_stub:
RETURN_BACK
@@ -183,6 +190,11 @@ NESTED(ftrace_graph_caller, PT_SIZE, ra)
jal prepare_ftrace_return
nop
MCOUNT_RESTORE_REGS
+#ifndef CONFIG_DYNAMIC_FTRACE
+#ifdef CONFIG_32BIT
+ addiu sp, sp, 8
+#endif
+#endif
RETURN_BACK
END(ftrace_graph_caller)
--
2.1.0
